In 1979, Omar Sharif, Michael Caine, and Peter Ustinov got together to make a film with a few scraped-together resources, much of it their own, with support acting from Rex Harrison and a then-retired (and very alcohol-dependent) William Holden. The film was titled in American release as Ashanti and was shot in the Sahara countries, including the Sudan. It depicted the reviving trans-Sahara slave trade, which Sharif (an Egyptian citizen) was at pains to denounce, since many of the buyers of this stream of slaves were Arabs. For audience interest, the plot was made to revolve around the kidnapping, transportation, and prospective sale of a babelicious Western doctor and her frantic husband's (Caine's) chase across the Sahara after her lowlife captors.
It was one of the last projects Holden was involved in. He died not long afterward, of a fall and head injury in his own living room.
The film didn't do much, but the people who did see it got an education -- which, as Sharif pointed out in an interview, is what this "cause film" was all about.
Ashanti----I'm gonna check it out.